AIDS Perspective

HIV disease and alpha interferon

I had intended to continue writing about individualization of treatment for HIV infection with an emphasis on the variability of the natural history of HIV disease.Instead, I will make an historical digression. I’ll do this from time to time. An account of the diverse AIDS related issues with which I have been involved since 1981 (and even before the epidemic was first recognized) is on my web site aidsperspective.net. I’m slowly adding content. This should speed up; a lucky circumstance has provided me with access to professional web advice. I have until now had to rely on “how to” articles to get the site going.Surprised that at 76 I have got this far.At the outset I had said that one purpose of this blog was to bring attention to the web site, and that is one reason for this short introduction.

This post is concerned with the connection between alpha interferon and AIDS.I should say connections; there are many.

Today, most people will probably only be aware of interferon in connection with the treatment of hepatitis C in HIV infected and uninfected individuals.The benefit conferred by interferon treatment to many people with Hepatitis C, even those co infected with HIV is tremendous. The FDA first approved interferon alpha for the treatment of hepatitis C in 1991.

There are many connections between interferon and AIDS; the first of these became evident in 1981, the year the epidemic was recognized.

People with AIDS produce large amounts of interferon themselves. The sustained production of large amounts of interferon by untreated HIV infected people with more advanced disease is not only a part of the disease, but the most compelling evidence suggests that its various actions contribute to producing some of the abnormalities associated with it.But, paradoxically, in the early years of the epidemic more was injected into patients in attempts to treat the underlying disease. (There is an important difference between this and treating Kaposi’s sarcoma or Hepatitis C in coinfected people with interferon).

That interferon can be seen as both contributing to the disease and also as a means of treating it makes for a confusing but interesting story [1]

It will be helpful to start with a very brief description of the interferon system.

The interferons – there are several types, are a family of proteins produced by vertebrates.They are cytokines, the name given to polypeptide or protein molecules produced by cells which act as signals that can influence their behavior, and that of other cells distant from the producing cell.In acting at sites distant from where they are produced, cytokines are akin to hormones.

All the interferons share some common properties, and it is easier to write about interferon in the singular.Interferon is best known for its broad antiviral effect.It is produced by cells in response to viral infections, and circulates to render other cells resistant to infection, thereby playing a central role in recovery.

Most viruses are sensitive to interferon and it was once hoped that interferon might prove to be a broad spectrum antiviral agent, similar to broad spectrum antibiotics that act against bacteria. There was great difficulty in purifying interferon for human use but in 1980 recombinant DNA technology permitted the manufacture of large amounts of pure interferon by inserting the gene for interferon into bacteria or yeast.Apart from its antiviral effect, interferon has numerous other effects, particularly on the function of the immune system.It can inhibit the growth of certain cancers, and has an inhibitory effect on new blood vessel formation. It therefore has been effective in the treatment of AIDS related Kaposi’s sarcoma.Unfortunately its clinical utility is more limited than originally hoped. Its greatest success is in the treatment of hepatitis C.Here are some brief reviews:

This paradoxical situation – in which interferon is seen at the same time to be harmful and helpful, has given rise to some peculiar interpretations. Research directions have been influenced; on balance the desire to treat HIV disease itself with interferon (as opposed to treating Kaposi’s sarcoma and Hepatitis C in coinfected individuals) has probably inhibited research into its role in pathogenesis. It is notable that the overproduction of alpha interferon, a striking abnormality in people with AIDS, known since 1981, was barely studied, let alone discussed, in the first years of the epidemic.

This strange story of a substance seen by some to be harmful, and by others to be beneficial in the same circumstances, is best told in the light of my own experiences in both fields; in AIDS and in interferon.

The two areas that have occupied my professional life have been the laboratory study of the mechanism of interferon’s antiviral action, and clinical work in HIV disease, providing direct medical care to a very large number of HIV infected people as well as conducting clinical and laboratory research on this disease.

In the strangest of circumstances these two fields came together as early as 1981.In that year, AIDS was first recognized, although I and others had already noted early manifestations of what was to be called AIDS among our patients.

The first information I received concerning the occurrence of Kaposi’s sarcoma in several gay men in New York City came from Dr Joyce Wallace.She had received a biopsy report of a diagnosis of Kaposi’s sarcoma in one of our patients.Joyce had called the National Cancer Institute to ask if there was a physician in New York who was familiar with what was then a very rare condition.She had been told that there were – I think at that time, about 20 men with this condition in New York who were under the care of Dr Alvin Friedman-Kien.

This was quite astounding. Unsurprisingly, I did not immediately connect this with what I had been seeing in my own practice, – enlarged lymph nodes, enlarged spleens, low white blood cell counts, low blood platelets among other abnormalities.

Jan Vilcek, who was head of the virology lab at NYU is an old friend and interferon colleague, and I knew Alvin, because he also worked in Jan’s laboratory.So I immediately called to obtain more information about this remarkable news.

Given my training and experience as a microbiologist and the nature of my practice, there was no question that I needed to contribute to the response.

So, in 1981, I also started to work in the virology laboratory at NYU.

I divided my time. Mornings were spent in the lab, and patients seen in the afternoons.

My work in the lab was initially focussed on cytomegalovirus (CMV) as there was evidence that many gay men at risk for this new disease were actively infected with this ubiquitous virus and excreting it at rates higher than noted in others. There also was literature at that time suggesting that CMV was involved in the development of non AIDS related Kaposi’s sarcoma (an idea that was not to hold up).

Once in the lab a strange circumstance brought interferon back into my life in connection with this new disease.

I read a preprint of a paper of Jan Vilcek’s where he described the ability of an antibody to lymphocytes – specifically anti CD3, to induce the synthesis of gamma interferon. Because of other observations that were made on our first patients, I had the idea that we would find gamma interferon in the circulation of patients with AIDS.This incident has been recorded and published by Jan Vilcek and an extract of the article can be seen by clicking here.

This is just the relevant part from a longer article, appearing in the annual “Interferon” series published by Academic Press and edited by Ion Gresser.

It explains how we came to look for interferon in the blood of people with AIDS.Alvin Friedman-Kien provided sera from his patients, andJan Vilcek provided just about everything else.Gene De Stefano, who is the lead author on the paper we finally published,[2] was a student working in Jan’s lab. The author’s names are in alphabetical order, as this seemed the best way to deal with the matter of precedence, as so many collaborators had become involved. I had sent sera to Robert Friedman in Bethesda, another old friend and interferon colleague, and we joined forces in pursuing this work.

As Jan Vilcek’s account describes, my idea proved to be wrong, the interferon we found was not gamma interferon, but alpha interferon.

Many years later gamma interferon was detected in the circulation of people with AIDS.

This was the first of many connections between interferon and AIDS, a connection made in the first year of the epidemic.

It immediately suggested that the sustained presence of large amounts of interferon in the circulation might be contributing to pathogenesis, and that there was an autoimmune component to AIDS. Apart from AIDS, at that time the only other situation in which there was the sustained presence of large amounts of interferon was in auto immune diseases such as lupus. Also, as individuals with various diseases, including Hepatitis C were treated with interferon, auto immune complications were noted among them.

Since I will be critical of some aspects of AIDS research in relationship to interferon it is very important that, before I get into this, I make the following point very clearly.

Interferon has been of inestimable value to people infected with Hepatitis C, including those coinfected with HIV. Interferon in combination with ribavirin has been able to cure many individuals of Hepatitis C infection.It has thus been life saving, as the consequences of Hepatitis C infections can include liver cirrhosis and liver cancer. It is probably the case that interferon’s greatest clinical triumph has been in the treatment of hepatitis C.At one time it was also the only available treatment for Hepatitis B.

So, to emphasize the point, interferon for the treatment of hepatitis C in HIV infected individuals can be life saving. It may be useful in some instances of Kaposi’s sarcoma unresponsive to antiretroviral drugs.

But I believe it has absolutely no place in the treatment of HIV disease itself.There are early reports of benefits conferred by interferon treatment [3] but there is also a great deal of persuasive evidence that long term treatment is hazardous[4].(This article contains numerous references supporting a role in pathogenesis for interferon).

So this is an illustration of the Jekyll and Hyde view of interferon.Does it mediate some of the pathological features of HIV disease, or should we use it to ameliorate these features?

On balance, I believe the evidence supports the view that overproduction of alpha interferon contributes to the manifestations of HIV disease. In specific instances, particularly in Hepatitis Cin coinfected individuals and in some cases of AIDS related Kaposi’s sarcoma, the benefits of interferon most definitely outweigh the risks.This is particularly true in people with higher CD4 counts.

Nonetheless overproduction of interferon is a feature of AIDS. But It took many years for work to be done to identify the interferon producing cell.This was achieved by Frederick Siegal in 1999.

Quite early in the epidemic, AIDS was described as a disease characterized by a dysregulation of cytokine production.Interferon is a cytokine, in fact the very first to have been described, but it rarely appeared in the list of cytokine abnormalities associated with AIDS.

Here are some of the biological effects of interferon that resemble features characteristic of HIV disease:

Interferon inhibits the development of white blood cells and platelet and red blood cell precursors. It causes fevers. It stimulates the production of a molecule called beta2microglobulin, which was used as an adverse prognostic marker in AIDS. It affects lipid metabolism and can cause an increase in serum triglycerides, observed in AIDS patients before the era of HAART. It modulates the activity of B cells, which make antibodies, and B cells are overactive in AIDS.

But perhaps of greatest interest is the ability of Interferon α to selectively inhibit the proliferation of the CD4 lymphocyte subset, a finding that was published as early as 1983.[5]It also has a slight stimulatory effect on CD8 lymphocytes.

This is the “dark and sinister” side to interferon.

Given these effects of interferon it is hard to understand what the researchers hoped to achieve by injecting yet more of into people who were already full of it.

Two reasons were givenfor administering interferon.Firstly interferon has antiviral properties. This rationale was resistant to the obvious problem that despite large amounts of interferon in the circulation, HIV continued to replicate. Indeed, as the disease progressed and viral production increased, so did the levels of interferon.

The second reason given was that cells taken from people with AIDS could not be stimulated to produce interferon in the test tube.This was an early finding of Dr Siegal.

The inability of cells from people with advanced HIV disease to make interferon in the test tube is actually exactly what is to be expected.It has been known for many years that when cells are exposed to large amounts of interferon for long periods, they cannot be stimulated to make interferon. They are in what is called a refractory state.The authors describing the inability of patient’s cells to make interferon seemed to not consider this, and so the strange idea that the inability to make interferon was an intrinsic abnormality in AIDS was advanced as a reason to administer interferon.

The inability to induce interferon production in cells derived from people with AIDS is indeed strange as the circulation from which they are removed is full of it. The interferon must come from somewhere. It is possible that it comes from cells in solid tissue. The reason for suggesting this is that membrane fragments from HIV infected cells are excellent inducers of interferon. This suggests that in the body, interferon may be made by cells that are in apposition to HIV infected cells in solid tissue.

This may be more difficult to study now.AZT promptly removes interferon from the circulation, and this is probably true for all effective antiretroviral drugs.

The prompt removal of interferon by antiretroviral treatment must make one wonder if this is at least part of the reason for the benefits of treatment. Inhibition of HIV replication, associated with the loss of circulating interferon definitely suggests that HIV is responsible for the high levels of interferon.

In this connection here are some results that we observed:

The solid line represents HIV levels, and the dotted line interferon levels.These two individuals, A and B were treated with AZT for one week at weekly intervals.Both interferon and HIVlevels promptly decline when on AZT and just as quickly go up when AZT is removed.

These three people started AZT at time 0. Both HIV (p24) and interferon rapidly decline.

These are individuals on continuous AZT therapy. Interferon rapidly declines in all, but returns at varying times despite continued treatment with AZT.Is it possible that the transient and variable duration of benefit experienced, coincides with the period when interferon is absent?

This is one person on continuous AZT treatment. Interferon starts to return and rise before 18 weeks.P24 only returns after 33 weeks.However this does not necessarily mean that interferon returns to the circulation before HIV.P24 measurements are not that sensitive and if PCR had been used HIV may have been detectable much earlier.

This is turning out to be a long post, and I will just make a few more points and end it.

When cells are exposed to interferon for prolonged periods several changes are noted in addition to their diminished capacity to make interferon when stimulated to do so.The antiviral action of interferon depends on the attachment of interferon to a specific cell receptor. The number of interferon receptors is reduced in cells taken from patients with AIDS, most probably as a result of exposure to endogenous interferon, and this may partly explain the diminished antiviral effect of interferon in advanced disease.This finding also has implications about possibly diminished effects of added interferon

From the point of view of interferon’s antiviral action only, it might seem advantageous for interferon to always be present. But there are active mechanisms to turn off its production, usually after a matter of days, which supports the view that prolonged exposure to interferon can be detrimental.Its many actions – other than its antiviral action are in fact deleterious.Apart from untreated HIV disease, lupus, an autoimmune disease is also associated with the sustained production of interferon α.There are studies in this disease on the mechanisms that sustain interferon production that may also have relevance to HIV disease. In HIV disease, it may of course be the persistence of HIV, but the opportunity to do study this has probably been lost as antiretroviral treatments remove interferon from the circulation.

When the question was asked, why add more interferon to people who already had lots of it, the answer was that the interferon already in the patient, (the endogenous interferon), was different to that to be injected.The basis for this claim of difference was that endogenous alpha interferon was unstable in acid, unlike conventional interferon.

But endogenous alpha interferon did everything that conventional interferon did – most importantly it had the same antiviral properties.Further, there was evidence that the acid instability was not an intrinsic property of the interferon molecule[6].

The neglect in pursuing a possible role in pathogenesis of high levels of circulating interferon was connected with a desire to use it to treat people with AIDS.This was a strange initiative. Apart from Kaposi’s sarcoma and hepatitis C it helped nobody in the long term and subjected people to extremely unpleasant side effects. Considering what interferon can do, one must wonder what effect it might have had on disease progression in the longer term.

Here is an extract from a transcript of a meeting in New York City that Dr Fauci attended to answer questions. This is the response to a questionabout administering interferon to people who already had more than enough of it in their circulation:

Fauci:

No. I think that acid-labile alpha interferon is an abnormal form of alpha interferon that really doesn’t have the same effects as the kind of interferon we’ve been infusing. It’s almost as though it’s two different drugs. It’s very confusing, because that’s been in the literature and in the paper a lot. It really is different. It’s different. It isn’t the same. There are some similarities, obviously, because it’s the same type of species of an agent, but there are some differences. Whether or not it’s doing harm or good, we don’t know, because there’s so many other things going on ………………………

Fouratt:…….

You said there are differences, and then you went on.But I didn’t hear what the differences were between the two.

Fauci:

Yeah.In vitro effects.Joe, you look like you had a question about that.

Sonnabend:

I’m not aware that there are any biological differences between acid-labile interferon and conventional interferon.Acid-labile interferon is neutralized by antibodies to conventional interferon. There’s been a recent report that, as you know, in lupus, a similar interferon appears, and there’s quite some conjecture that indeed it may play a role in pathogenesis. More recently, from Jan Vilcek’s lab, there’s been a demonstration that the acid lability may be due to another protein that sticks to it. If that’s so in lupus, my guess is that there’s no reason to think it’s different in AIDS. As far as I know the biological properties of acid- labile interferon are identical to those of –

Fauci:

Yeah, well –

The other argument for using treatment with interferon was that cells from AIDS patients could not make interferon.As noted, the problem with this justification is that the people from whom these cells were taken were full of interferon, which had to come from somewhere. So if the cells taken from the patients were unable to be stimulated to make interferon, other cells are actually overproducing it.

There are still some attempts to treat HIV infection (as opposed to hepatitis C and Kaposi’s sarcoma) with interferon. It is possible that a place may eventually be found for its use, but this would almost surely be on temporary basis and in those who do not already have interferon in their circulation.

The presentation made in 1991 from which the figures in this post were taken can be seen by clicking HERE; there are a few contemporary annotations.

[1]“For, like the character of Dr Jekyll and Mr Hyde, interferon , while possessing great virtues, has a dark and sinister side”Susan Krown, in “Interferon 7” 1986 Academic press p 185-211

Some immunologic parameters in homosexual patients with Kaposi’s sarcoma (KS) or unexplained lymphadenopathy resemble findings in patients with autoimmune diseases such as systemic lupus erythematosus (SLE). Many patients with SLE have an unusual acid-labile form of human leukocyte interferon (HuIFN-alpha) in their serum. Sera from 91 homosexual men were tested for the presence of HuIFN. Of 27 patients with KS, 17 had significant titers of HuIFN in their serum. Ten of 35 patients with lymphadenopathy and three of four patients with other clinical symptoms also had circulating HuIFN. In contrast, only two of 25 apparently healthy subjects had serum HuIFN. All 32 samples of Hu IFN had antiviral activity on bovine cells, a characteristic of HuIFN-alpha, and all of 14 representative samples tested were neutralized by antibody to HuIFN-alpha. In addition, the HuIFN-alpha in six of eight representative patients was inactivated at pH 2 and therefore appears to be similar to the HuIFN-alpha found in patients with SLE. These findings suggest that an autoimmune disorder may underly lymphadenopathy and KS in homosexual men.

Mixed lymphocyte reaction (MLR) cultures of human lymphocyte subsets with or without the addition of physiological doses of human alpha interferon (IFN-alpha) were compared with respect to surface marker phenotypes and proliferative capacities of the responder cells. A selective depression on the T4 (inducer) T-cell subset could be demonstrated as a sequence of events: decreased fluorescence intensity of the T4 inducer cells (day 2 of culture), decreased percentages of T4 cells as demonstrated by cell cytofluorometry (days 3-6 of culture) , and decreased 3H-thymidine incorporation of purified T4 cells and decreased numbers of T4 cells harvested from IFN MLRs (days 5-6 of culture). In contrast, it was shown that the T8 (cytotoxic/suppressor) subset in MLRs was either not affected or slightly stimulated by the addition of IFN. The depression of the T4 cells by IFN was accompanied by a decrease in the number of activated T cells expressing Ia antigens. On the other hand, IFN MLRs contained greater numbers of cells expressing the T10 differentiation antigen. In experiments with purified T-cell subsets the IFN effect was exerted directly on the T4 cells and not mediated by either T8 suppressor cells or monocytes. These findings are discussed in relation to other immunoregulatory effects of IFN-alpha.

[6] Endogenous “acid labile” interferon is neutralized by monoclonal antibodies against conventional “acid stable” interferon. The amount of interferon in a preparation was measured by observing how much the interferon containing sample could be diluted before it lost antiviral activity. Samples from patients contained antiviral molecules other than alpha interferon, and those that synergized with alpha interferon to increase its effects. Gamma interferon and TNF would be examples. These are destroyed by acid – not the interferon.

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